Hydrocarbon hydrocracking process and catalyst therefor



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HYDROCARBON HYDROCRACKING PROCESS AND CATALYST THEREFOR Louis Schmeriing, Riverside, 111., assignor, by mesne assignments, to Universal Oil Products Company, Des Plaines, lll., a corporation of Delaware No Drawing. Application September 21, 1953 Serial No. 381,498 2 Claims. (Cl. 208-112) This'invention relates to a process and catalyst for converting hydrocarbonaceous material and particularly v version conditions with a catalyst containing a tin halide and aluminum.

In another specific embodiment the present invention relates to a process for hydrocracking a hydrocarbon fraction by contacting the fraction to be hydrocracked, at a temperature of from about 700 F. to about 1200 F. and at a pressure of from about 100 p.s.i. to about 10,000 psi. or more in the presence of hydrogen, with a catalyst comprising tin halide and aluminum.

Although the process of the present invention may be applied to the conversion of many materials including gasoline, kerosene, gas oil, powdered coal, shale, tar sands, etc., it is particularly useful in processing residuum fractions such as topped crude, reduced crude, cracked residuum, etc. The problem of converting residuum fractions is particularly acute since the demand for the lighter petroleum fractions has increased while crudes, as they come from the well, have been increasingly carbonaceous and lacking in light material.

Thermal cracking processes and catalytic cracking processes using solid siliceous type catalysts are not well adapted for use with residuum fractions since the coke formingtendencies of residuum fractions preclude long active life of such a catalyst. Similarly, the coke forming tendencies of a residuum fraction reduce the time that a thermal cracking unit may remain on stream so that economical operation is diflicult. Furthermore, thermal treatment of a residuum fraction results in excessive losses in yield because of the non-selective nature of the destructive reactions which cause a large amount of gaseous material to be formed.

The present invention provides a means of converting a highly carbonaceous material and reducing the average molecular weight of the material by a process that does not form excessive gas or coke. As will be shown, by practicing the present invention, unexpectedly high yields of gasoline may be obtained with little formation of coke or normally gaseous material.

Following are three examples which illustrate the exceptional catalytic properties of the catalyst of this invention and other examples which illustrate that the catalyst of this invention is unique both in the amount of -re action promoted and in the selectivity of the reactions.

Example I 200 grams of East Texas topped crude were placed in aglass lined rotating autoclave 20 grams of stannous chloride dihydrate and 5 grams of granular aluminum metal under a hydrogen pressure of atmospheres. The contents of the bomb were agitated and heated to 750 F. for a period of 4 hours, after which the bomb and its contents were cooled. A final pressure of 30 atmospheres was observed. The contents of the bomb were discharged and an examination showed an 81 weight percent liquid yield, of which 62% boiled in the gasoline range, thus amounting to a conversion to gasoline of 50% of the topped crude charged to the autoclave. About 5 weight percent of the topped crude was recovered as a coke-like deposit mixed with the catalyst.

Similar results were obtained when 200 grams of the topped crude was treated under the same conditions in the presence of a mixture of 20 grams of anhydrous stannous chloride and 5 grams of aluminum granules. A76

weight percent yield of liquid product containing 65% of gasoline was obtained, which amounted to a gasoline yield of 50% based on the topped crude charge.

Example 11 200 grams of East Texas topped crude, 20 grams of stannous bromide and 5 grams of metallic aluminum pellets were placed in a glass lined rotating autoclave under 100 atmospheres of hydrogen pressure. The contents of the autoclave were agitated and heated to a temperature of 750 F. for 4 hours, after which the autoclave and its contents were cooled and a final pressure of 20 atmospheres was observed. The contents of the autoclave .were discharged and upon analysis revealed an 87 weight percent liquid yield of which 50% was gasoline, which amounts to 44 weight percent of gasoline yield based on the charging stock. There was a coke deposit amounting to 2 weight percent of the charge stock.

Example 111 Not only the stannous halide-s but also the stannic halides may be used in the process of this invention. Thus, when 200 grams of East Texas topped crude were treated under the reaction conditions of Example I using 5 grams of aluminum mixed with 20 grams of stannic chloride pentahydrate instead of 20 grams of stannous chloride dihydrate, there was recovered 73 weight percent of liquid product containing 70.5% of gasoline. This is equal to a 52 weight percent yield of gasoline based on the charge.

As will be seen from Examples 1, II, and III, the use of a tin halide in conjunction with metallic aluminum produces a catalyst which causes hydrocracking without excessive sludge formation and results in a high yield of gasoline from a residuum charge stock which is extremely difiicult to process by ordinary cracking methods. In an effort to determine exactly what the catalytic substance is, a series of experiments were conducted.

Example IV contents were then cooled and a final pressure of 70 atmospheres was observed. The contents of the autoclave were discharged and upon analysis it was found that a liquid yield of 92 weight percent was recovered; 8% of the liquid boiled in the gasoline range, amounting to 7% gasoline yield based on the total charge stock. Example Example V It was then thought that perhaps the catalytic substance was aluminum halide which would be formed by the interaction of the halide of a relatively electro-negative substance such as tin in the presence of metallic aluminum. In accordance with this, the following ex periment was conducted.

200 grams of East Texas topped crude and 20 grams of aluminum chloride were charged to a glass lined rotating autoclave, placed under a hydrogen pressure of 100 atmospheres and heated to a temperature of 750 F. for a'period of 4 hours, after which the autoclave and its contents were cooled and a final pressure of 52 atmospheres was observed. The contents of the autoclave were discharged and an analysis revealed that the liquid yield was only 47 weight percent of the charge stock, of which 64% boiled in the gasoline range, amounting to 30% yield of gasoline. 22 weight percent of the charge stock was recovered as coke on the catalyst. Although Example V illustrates that aluminum chloride is an active destructive reaction catalyst, the reaction is non-selective as shown by the low liquid yield and the low gasoline production. The non-selectivity and accordingly high gas and coke losses are reasons that aluminum chloride as such is not being utilized commercially. In contrast the catalyst of the present invention is very active and results in high yields of liquid products and of gasoline, with low gas and coke losses.

Example VI In order to determine whether it is necessary to have aluminum in the metallic state present in the reaction zone an experiment was conducted in which combined aluminum was used. Example VI illustrates the results of this experiment.

A catalyst was prepared by impregnating alumina pills with .stannous chloride. The resulting solid catalyst was charged to a glass lined rotating autoclave with 200 grams of East Texas topped crude and the resultant mixture was placed under a hydrogen pressure of 1.00 atmospheres and heated to a temperature of 750 F. for 4 hours. The autoclave and its contents were cooled and a final pressure of 88 atmospheres was observed. The contents of the autoclave were discharged and it was .tound that there was a 93 weight percent liquid yield of which 9% boiled in the gasoline range. This amounted to only an 8% conversion to gasoline based on the charge stock.

Example VII It was decided to determine whether or not the use of tin halide was essential or whether a halide of any metal which is electronegative as compared with aluminum might be equivalent to tin since any .such electronegative metal halide would cause nascent aluminum chloride to be produced in the reaction zone. Example VII illustrates the results of one such experiment.

200 grams of East Texas topped crude, 20 grams of nickel chloride hexahydrate, and grams of aluminum pellets were charged to a glass lined rotating autoclave and placed under a hydrogen pressure of 100 atmospheres. The autoclave and its contents were heated to a temperature of 750 F. for a period of 4 hours after which it was allowed to cool. A final pressure of 85 atmospheres was observed. The contents of the autoclave were discharged and upon examination were revealed to contain 93 weight percent liquid recovery of which 15.5% was gasoline, amounting to a conversion to gasoline of 14 weight percent base-d on the charge stock.

Example VIH i It was also thought that perhaps the aluminum pori mine whether an equivalent catalyst could be made by using a metal other than aluminum.

200 grams of East Texas topped crude, 20 grams of stannic chloride pentahydrate and 5 grams of pelleted magnesium metal werecharged to a glass lined rotating autoclave and placed under a hydrogen pressure of 100 atmospheres. The autoclave and its contents were heated to a temperature of 750 F for a period of 4 hours after which "the autoclave and its contents were cooled and a final pressure of 98 atmospheres was observed. The contents of the autoclave were discharged and subsequent examination revealed that there was a weight percent liquid yield of which 5% boiled in the gasoline range amounting to approximately a 5% conversion to gasoline based on the charge stock.

- Example 1X A This example reports an experiment which was carried out to show that alloys containing aluminum can be used in the catalyst of this process as well as aluminum metal itself.

200 grams of East Texas topped crude, 20 grams of stannous chloride dihydrate and 20 grams of Devardas alloy (an alloy of 10 parts aluminum, 9 parts copper and 1 part zinc) were charged to a glass lined rotating autoclave under a hydrogen pressure of 100 atmospheres. The autoclave and its contents were heated to a temperature of 750 F. for a period of 4 hours after which they were cooled and a final pressure of 26 atmospheres was observed. The contents of the autoclave were discharged and upon examination it was found that there was a 63 weight percent liquid yield of which 71% boiled in the gasoline range which amounted to a 45 weight percent conversion to gasoline based on the original charge.

Example X Although the presence of hydrogen in the reaction zone is a preferred embodiment of this invention, the catalyst is effective in the absence of hydrogen. The following experiment illustrates the eliectiveness of the present catalyst in an inert atmosphere.

200 grams of East Texas topped crude, 20 grams of stannous chloride dihydrate, and 5 grams of granular aluminum metal were placed in a glass lined rotating autoclave under a nitrogen pressure of 100 atmospheres. The contents of the bomb were agitated and heated to 750 F. for a period of 4 hours, after which the bomb and its contents were cooled. The final pressure was 103 atmospheres. The contents of the bomb were discharged and an examination showed a 75 weight percent liquid yield of which 45.5 weight percent boiled in the gasoline range,

amounting to 34 weight percent gasoline yield based on the charge. A coke-like deposit from the bomb represented 10 weight percent of the charge.

The gasoline from this example contained 12.3 vol.

percent olefins, contrasted to 3.2'vol. percent olefins in the gasoline of Example I, which was identical to Example X except that a hydrogen atmosphere was present. A comparison of these examples (Example X and Example I) shows that a hydrogen atmosphere is not essential to the operation but the presence of hydrogen improves the process by improving yields, diminishing coke formation and producing a more desirable (less unsaturated) product. I

From the foregoing examples it may readily be seen that a catalyst consisting of tin halide and aluminum metal has special desirable properties of selectivity and high activity. The specific catalyst of the present invention gives yields in the range of 50% gasoline and little'forrnation of coke and normally gaseous products. The yields and selectivity of this specific catalyst cannot be duplicated by catalysts composed of similar materials, such as other metal halides with aluminum, or metals such as magnesium with ,tin halides. Although a catalyst consisting of anhydrous aluminum chloride showed high activity, the products of a run using this catalyst were typical of extreme destructive reactions in that the product distribution was not selective and there was a large loss in yield due to coke and gas formation. Although the exact mechanism of the reaction is not known, it appears that the catalytic substance may be an intermediate compound resulting from an interaction between the bi-metal couple consisting of aluminum and tin. As indicated by the examples neither tin chloride nor aluminum chloride by itself is the catalyst and the presence of chloride with aluminum metal is not the catalyst either. The examples also demonsrate that the presence of tin is necessary and not metals having similar characteristics.

As is indicated by the examples, the tin halide of the present catalyst may be in either the stannous or stannic state of oxidation and may be either anhydrous or in any hydrated form. The preferred halides are the chlorides and bromides, however, the iodides show good catalytic activity although their cost may be prohibitive.

The tin halide of the present catalyst may be formed in situ by adding, for example, stannous oxide and aluminum metal to the reaction zone and mixing hydrogen chloride or hydrogen bromide with the charge stock. The addition of alkyl halides, for example, t-butyl chloride, propyl chloride, amyl chloride, etc., to the reaction zone wherein hydrogenating conditions are maintained, is another method of forming tin halide in situ.

For the sake of comparison the examples all illustrated the process of the present invention as eiiected at 750 F. and 100 atmospheres of hydrogen pressure; however the process may be operated at different conditions. The process may be effected at temperatures of from about 650 F. to about 1200 F. or more, depending upon the degree of reaction that is desired and the characteristics of the charge stock. It is desirable to operate at a higher temperature when a more refractory charge stock, such as a residuum fraction admixed with a high proportion of recycle stock, is to be processed. It will also be desirable to operate at a higher temperature when a lighter charge stock such as kerosene is to be processed in that the smaller molecules of a light fraction are more resistant to destructive reactions.

Inasmuch as, in one embodiment, the reaction effected by the present process is a combination of cracking and hydrogenation, it will be desirable to operate at as high a pressure as is practical since high pressure favors hydrogenation reactions. It is contemplated that pressures ranging from about 100 p.s.i. to about 10,000 p.s.i. or more may be used depending upon the product desired and the characteristics of the charging stock. When a highly unsaturated charge stock, such as a stock contain ing a high proportion of cycle stock, is used, it will be desirable to operate at a higher pressure to diminish the amount of coke formation due to the polymerization of unsaturated material. High hydrogen pressures will cause a more rapid saturation of unsaturated material, thereby diminishing the opportunity for polymerization since a saturated material has no polymerizing tendencies.

Ordinarily the hydrogen will be recirculated through the system and passed through the reaction zone concurrently with the charge stock. The hydrogen will preferably be in a mol ratio of from about 1 to about 20 mols of hydrogen per mol of hydrocarbon charged. The hydrogen need not be pure and it may contain up to 50% of contaminants such as hydrocarbon gases having from one to four carbon atoms or oxides of carbon. The gas may be recycled within the process or it may be obtained from other refinery sources such as the net gas make from a reforming process.

Ordinarily the pressure will be selected to be consistent with economical plant design as well as with the most favorable operating and equilibrium conditions. When a saturated product is not desired, the process may be operated at atmospheric pressure or under a superatmospheric pressure of nitrogen, methane, other hydrocarbon gases, carbon monoxide, carbon dioxide, or other gases.

The process of the present invention may be effected in any suitable apparatus. Since, at the temperature of the reactions, the tin halides will generally be in the liquid state, the process may be effected by passing the hydrocarbon through a molten bath of tin halide in which finely divided aluminum is suspended. In such an operation it is preferred that the hydrocarbonaceous material passes upwardly through the bath of molten halide so as to cause turbulence in the molten mass thereby keeping the aluminum metal in suspension. The hydrogen-containing gas may be introduced through high velocity jets which will also create turbulence in the reaction zone. However, it is preferred to mix the hydrogen with the charge stock prior to introduction into the reaction zone. The process of the present invention may also be effected in slurry or fluidized operations wherein the catalytic material and the material to be converted flow concurrently through -a reaction zone wherein the desired reactions are eifected and are subsequently separated into a catalyst and a product stream. Some tin halides are soluble to some extent in some of the hydrocarbons and may be used as a homogeneous catalyst with particles of aluminum suspended therein or the charge stock and molten catalyst be formed into finely divided dispersions by mechanical agitators maintained in the reaction zone. The apparatus for effecting this process may contain means for removing solid carbonaceous matter from the molten bath. Such means may include floating coke from the surface of the molten mass, passing all or a portion of the product stream through a screen, burning the small amount of coke that is formed from the molten catalyst to prevent a buildup, preferably in a zone remote from the reaction zone, etc. The latter method is especially desirable when endothermic reactions are being effected. The process will generally include recycling of a portion of the process gas as well as recycling of at least a portion of the uncracked material from the product stream.

The proportion of tin halide to aluminum metal in the catalyst mixture is not critical. In a commercial operation it may be necessary to continuously add both aluminum metal and tin halide to the reaction zone to make up for the material lost in the product stream. A means of continuously recovering any small amounts of halides dissolved in the hydrocarbon product may be employed so that these losses are diminished. Such means may include fractionation, cooling to reduce solubility, fractional crystallization, or preferably extraction with water since the halides are quite soluble therein.

Although it is not necessarily preferred, impure aluminum or aluminum alloys may be used to form the catalyst of this invention. One such alloy is an aluminum-copperzinc alloy as described in Example IX, however, alumihum-copper alloys and others may be used.

Small amounts of hydrogen halides may also be used in the reaction zone, especially if an alkaline impurity is present in the charging stock. The hydrogen halide or alkyl halides may be used to form tin halides in situ or as an additional component.

I claim as my invention:

1. A process of hydrocracking a hydrocarbon which comprises contacting said hydrocarbon at a temperature of from about 650 F. to about 1200" F. and a pressure of from about p.s.i. to about 10,000 p.s.i. of hydrogen with a catalyst comprising a tin halide and aluminum metal.

2. A catalyst comprising stannous chloride dihydrate and aluminum metal.

References Cited in the file of this patent UNITED STATES PATENTS 1,937,946 EglofE Dec. 5, 1933 2,100,354 Pier et al Nov. 30, 1937 2,436,774 Nuttiug et al. Feb. 24, 1948 

1. A PROCESS OF HYDROCRACKING A HYDROCARBON WHICH COMPRISES CONTACTING SAID HYDROCARBONAT A TEMPERATURE OF FORM ABOTU 650*F. TO ABOUT 1200*F. AND A PRESSURE OF FROM ABOUT 100 P.S.I. TO ABOUT 10,000 P.S.I. OF HYDROGEN WITH A CATALYST COMPRISING A TIN HALIDE AND ALUMINUM METAL. 